The present invention, which is the improvement of U.S. Pat. No. 5,459,116, relating to a catalyst for polymerization and copolymerization of olefin, particularly relates to a catalyst for production of polymers, which has high activity and provides polymer with narrow molecular weight distribution, and narrow particle size distribution, yielding small amount of low polymers.
Prior arts in olefin polymerization or copolymerization are the two: either production of solid catalytic components by reacting, with a halogen-containing titanium compound, the compound produced by reaction of a magnesium compound with alcohol, organic carboxylic acid, aldehyde, and amine and their mixture, in an inert hydrocarbon solvent; or production of solid titanium catalytic components by first producing an active carrier by the use of a halogen-containing silicon compound, tin compound, or an aluminum compound as recrystallized compounds, and next by contacting it with a titanium halide compound.
Now, U.S. Pat. Nos. 4,336,360 and 4,330,649 describe a method for producing a polymerization catalyst with high activity containing titanium components, by liquefying a magnesium carrier by reacting it with an electron donor such as alcohol in a hydrocarbon solvent, reacting it with such a halogen compound as silicon tetrachloride, which is a recrystallization process of the magnesium carrier component, in order to produce a solid magnesium carrier, and after all these processes, by having it supported by such a titanium compound as titanium tetrachloride, or by having it precipitated by pouring in titanium tetrachloride. But when olefin is polymerized or copolymerized with the use of a catalyst produced in the way given above, the resultant polymer has too much of fine powder, the particle size distribution being broad, and the bulk density low. Other defects include a rather broad molecular weight distribution and the yield of so much of low polymer soluble in such a solvent as hexane at the time of slurry polymerization. Here, a low polymer means a polymer which usually has a melting index of over 5000 and a molecular weight of under 1000.
U.S. Pat. No. 5,419,116, on the other hand, describes a method for producing a solid polymerization catalyst containing a magnesium compound, titanium compound, and electron donor components, for the purpose of remedying such defects of conventional catalysts as indicated above and yielding a catalyst possessed of a high activity, greater bulk density, by first liquefying a magnesium compound by reacting it with an electron donor such as alcohol in a hydrocarbon solvent, then, after reacting it with an ester compound having at least one hydroxy group, getting it to precipitate by reacting with such a titanium compound as titanium tetrachloride.
However, if olefin polymerization or copolymerization is performed with the use of such a catalyst produced that way, the catalyst does show a high activity and the resultant polymer has a merit of relatively high bulk density, but it nevertheless has such demerits as a broad particle size distribution, a broad molecular weight distribution, and a large yield of low polymer soluble in the solvents such as hexane at slurry polymerization.